To counter the threat of terrorism, there is a requirement for systems to be put in place to detect and address subversive activity. Some of such systems known in the art are purely designed to detect subversive activity; others are designed to prevent subversive activity; while still other known systems are designed purely as a deterrent. For example, some systems are primarily physical (such as barriers and security agents), some rely on networks of sensors (such as CCTV systems) while others involve dedicated installations (such as radio jamming mast or X-ray scanning machines).
What is needed, however, are covert surveillance systems that are highly mobile, can be rapidly deployed and allow the use of a plurality of surveillance data to enable more informed, robust and intelligent threat detection and prevention.
Accordingly, there is need for a covert mobile inspection vehicle that uses a plurality of prevention and detection components or sensors.
There is also need for a system that intelligently integrates and/or correlates surveillance information from the plurality of multi-modality sensors to detect and prevent subversive activities.
Further, among detection systems that provide for efficient non-invasive inspection, X-ray imaging systems are the most commonly used. Transmission based X-ray imaging systems are traditionally used to inspect trucks and cargo containers for contraband. Inspection of a certain larger structures, such as complete aircraft, however, can be challenging with a transmission-based geometry wherein, typically, the source is located on one side of the aircraft and detectors are located on the other side of the aircraft. This geometry has many challenges, and in particular, when scanning around the landing gear and engines there is difficulty in placing detectors and thus, in producing radiographic images.
In backscatter-based inspection systems, X-rays are used for irradiating a vehicle or object being inspected, and rays that are scattered back by the object are collected by one or more detectors. The resultant data is appropriately processed to provide images which help identify the presence of contraband. Since aircraft are typically made of lighter materials, a backscatter-based detection system would provide adequate penetration in most cases and thus would only require equipment to be placed on one side of the aircraft.
However, backscatter technology may not be suitable when all areas of the aircraft have to be penetrated with a high detection probability, such as is the case with nuclear materials detection. Areas of high attenuation as measured by the backscattered radiation include fuel tanks, transformers, counterweights, among other aircraft components. In addition, backscatter technology cannot effectively discriminate between typical metals and special nuclear materials.
Aircraft inspection calls for unique requirements such as the capability of inspecting large aircraft from more than one side. In addition, varying aircraft sizes would require the inspection head to scan at different heights, and several sections of the aircraft, such as the wings and tails, would require different head and detector scanning configurations. Conventional X-ray backscatter and transmission systems, however, do not have adequate scanning robustness, ability to work in various orientations, scanning range, or field of view for aircraft inspection applications.
There is also a need to detect partially shielded or un-shielded special and radiological materials using passive detection technology.
There is an even greater need to perform active and passive measurements simultaneously to prevent re-scanning the object or to avoid having two separate screening systems.
In passive radiation-based detection systems, radiation emitted from special and radiological materials is measured without active interrogation. It is challenging, however, to combine both active backscatter inspection and passive radiation detection while still ensuring that the backscatter beam signals do not interfere with passive detection techniques, because the high backscatter radiation will impinge upon passive detectors at the same time the low-intensity passive signals are measured.
Therefore, what is needed is a method and system for detection of both active backscatter and passive radiation, and in particular, simultaneous inspection.
What is also needed is an active and passive detection system that is easily transportable, mobile, and non-intrusive, that is capable of operating even in rugged outdoor conditions such as airport environments.